Losing Prime

Bluestorm · 07-07-2007, 03:00 PM

I have a 02, 2500 HD, Duramax engine that is losing prime. I have replace both rubber fuel lines coming from the fuel filter. I have replace the fuel filter twice, once with an after-market and now back to the OEM filter. I have replace the water sensor at the bottom of the fuel filter. I have been told that it might be my fuel pump which has a one-way flow valve that has become stuck allowing fuel to flow back to the tank. I'm out of ideas. If I let my truck set around 6 hrs or overnight, when I crank it, it runs around 20 seconds then shuts off and I have to re-prime it. The problems has gotten worst over time, I used to just park my truck with the engine facing downward on a slight grade and I would not lose prime, but now I'm losing prime everyday. Does someone have any advise?

**ob_1jr** · 07-07-2007, 04:17 PM

check that plastic bleeder screw on top. It could be cracked or the o-ring on it could be bad. The only other thing that it could be is a cracked filter housing. Are you sure both o-ring and gasket came off with the old filter? If it is the filter housing, your best bet would be to try and find one off e-bay or contact Eric Merchant at Merchant Automotive (gmdieseltech.com). They are pretty expensive from the dealer. (like $700 IIRC)

Bluestorm · 07-07-2007, 04:51 PM

I have also replace the plastic bleeder screw with a new one and I did remove both the o-rings and replaced them with a new one. I'll check the filter housing, Thanks

slamdxterra · 07-08-2007, 09:20 AM

i kinda have the same problem. I keep gettin air in my fuel system after long drives. Once you turn it off and try to start it wont start at all. I have to prime and bleed it like you ran it out of diesel. The pressure is good but theres alot of air bubbles in the diesel. WHATS THIS FROM? Please help. I have changed the plastic bleed screw, new filter and gasket even from the dealer twice!

**ob_1jr** · 07-08-2007, 10:49 AM

Sounds like you have the same problem....unfortunately it probably won't be cheap. Sounds like the filter head unit. Probably from your prime pump or if you ever had the dealer change the filter....could have had the "filter gorilla" put it on and crack the housing. How does your water in fuel sensor look? There could be a hairline crack in that causing your problem too and not dripping on the ground.

Bluestorm · 07-08-2007, 01:59 PM

Can you just bypass the stock filter, by installing a after-market filter system. The only thing about most of the after-market filters is that theire isn't a priming bulb. Is a priming bulb required?

**ob_1jr** · 07-08-2007, 04:11 PM

Yes, there is such a system that most people put post OEM filter and I have seen one that has a prime bulb. I would just make sure that it has a fuel heater if you live in a place that it get cold like below 0...but as far as warranty is concerned, I don't know what the dealer would say if you went in for injectors. Those systems could cost nearly as much as an OEM set-up would. They are nice though since it could be mounted where the second alternator would go.

duramax06 · 07-08-2007, 08:33 PM

EDIT* nvm, found my own answer

slamdxterra · 07-08-2007, 08:35 PM

I took it into the dealer and they traced it down to a a fuel filter. I knew it wasnt tho cuz i just had it changed a month prior. It starts right up like it should after i change the filter. After some miles and driving for at least 30 mins it wont start up. Seems like longer you drive the harder it is to start if it doesnt fully cool down! The dealer looked at the fuel filter head unit and said it was fine. I havent checked the water sensor yet! Goin into the dealer tomorrow for injectors. Should i get a new water sensor?

**ob_1jr** · 07-08-2007, 08:39 PM

Do you have a wet spot on your frame? You could pick one up, but I don't know if it will help at all. It could be something associated with the injectors too.